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use std::cell::RefCell;
const LOG_MESSAGES_BYTES_LIMIT: usize = 10 * 1000;
#[derive(Default)]
struct LogCollectorInner {
messages: Vec<String>,
bytes_written: usize,
limit_warning: bool,
}
#[derive(Default)]
pub struct LogCollector {
inner: RefCell<LogCollectorInner>,
}
impl LogCollector {
pub fn log(&self, message: &str) {
let mut inner = self.inner.borrow_mut();
if inner.bytes_written + message.len() >= LOG_MESSAGES_BYTES_LIMIT {
if !inner.limit_warning {
inner.limit_warning = true;
inner.messages.push(String::from("Log truncated"));
}
} else {
inner.bytes_written += message.len();
inner.messages.push(message.to_string());
}
}
}
impl From<LogCollector> for Vec<String> {
fn from(log_collector: LogCollector) -> Self {
log_collector.inner.into_inner().messages
}
}
#[cfg(test)]
pub(crate) mod tests {
use super::*;
#[test]
fn test_log_messages_bytes_limit() {
let lc = LogCollector::default();
for _i in 0..LOG_MESSAGES_BYTES_LIMIT * 2 {
lc.log("x");
}
let logs: Vec<_> = lc.into();
assert_eq!(logs.len(), LOG_MESSAGES_BYTES_LIMIT);
for log in logs.iter().take(LOG_MESSAGES_BYTES_LIMIT - 1) {
assert_eq!(*log, "x".to_string());
}
assert_eq!(logs.last(), Some(&"Log truncated".to_string()));
}
}